Fibroplasia, a constant and necessary sequela to the inflammatory process, may be directly influenced by the inflammatory exudate. The macrophage, a prominent component of inflammatory exudates has recently been implicated in the elaboration of a variety of substances which may have profound qualitative and quantitative influences on the progression of tissue destruction and healing in inflamed tissues. The principal objective of this proposal is to determine the effects of materials released from macrophages on the survival and proliferation of human gingival fibroblasts in vitro. Furthermore, this proposal seeks to develop procedures for the identification, purification and chemical and physical characterization of the pertinent macrophage associated substances. Fibroblasts quiescent (low fraction of cell population traversing cell cycle) in human platelet poor plasma serum (PPPS) or platelet poor plasma (PPP) supplemented minimal essential medium will be treated with PPPS or PPP medium which has been exposed to rat macrophages obtained and cultured under a variety of conditions. The effects of this treatment on the accumulation of these cells in culture will be determined. These observations will be followed by experiments designed to (a) manipulate the relevant conditions to optimize the observed effects, (b) determine the means by which these changes are effected and (c) to utilize the response of these cells as a bioassay system to monitor the progress of experiments designed to purify and characterize the pertinent active macrophage related material(s).